1. Field of the Invention
The present invention relates generally to the field of electromagnetic devices for completing and interrupting current carrying paths between a source of electrical power and a load. More particularly, the invention relates to a novel technique for forming an electromagnetic operator which serves to complete and interrupt the current carrying paths in such devices upon the application or removal of control signals.
2. Description of the Related Art
A wide variety of electromagnetic devices have been devised for completing and interrupting current carrying paths between electrical sources and loads. In several families of such devices an electromagnet is formed by winding a conductive wire around a core. A field is generated by the electromagnet upon application of a current through the winding. The field is used to attract an armature which, in turn, causes displacement of movable contacts within the device. Depending upon whether the device is coupled in a normally open or normally closed orientation, the control signals may thereby complete a current carrying path through the device, or interrupt the path. Upon removal of the control signal from the actuator coil, biasing members such as compression springs are often employed to return the armature and movable contacts to their normal or biased position.
While devices of the type described above are generally suitable for many applications, they often include a large number of individual parts which must be separately designed, manufactured and assembled. For example, in a conventional contactor, an operator assembly, including the electromagnet coil is assembled around the coil or the coil bobbin in one portion of the contactor, while stationary and movable contacts are assembled in another portion of the device. Even in relatively small, single-phase devices, the resulting number of individual parts is fairly large. In larger, multi-phase devices, the number and size of the individual components is substantially increased, although certain components may be shared between power phase sections. As the number and complexity of the individual components of these devices increases, so does the cost both in terms of design, manufacturing, tooling, and assembly. Moreover, an increased complexity of the device sometimes gives rise to an increased risk of failure of individual components or subsystems which can reduce the useful life of the entire device package.
There is a continuing need, therefore, for an improved operator structure that can be used in electromagnetically-operated devices, such as contactors, circuit interrupters, switch gear, motor starters, and so forth. There is a particular need for relatively simple structures which can be manufactured of readily available materials and which is extremely robust. Such improved structures are advantageously actuated and returned to a normal position by means which do not require excessive power input as control signals.